One staggering on all fours (7)

I believe the answer is:

lurcher

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'one staggering' is the definition.
(I've seen this before)

I can't explain the remainder of the clue.

(Other definitions for lurcher that I've seen before include "Not a sure-footed" , "Crossbred hunter" , "moving suddenly and unsteadily?" , "Greyhound-like dog" , "inclined to leave people in difficulties?" .)

I've seen this clue in The Globe and Mail and The Guardian.

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